/Engine/Plugins/Runtime/Metasound/Source/MetasoundFrontend/Public/MetasoundRouter.h
For generic senders for copyable types:
namespace Metasound { template<typename TDataType, typename [TEnableIf](API\Runtime\Core\Templates\TEnableIf)< [TIsDerivedFrom](API\Runtime\Core\Templates\TIsDerivedFrom)< TDataType, IAudioDataType >::Value, bool >::Type> [TSenderPtr](API\Plugins\MetasoundFrontend\TSenderPtr)< TDataType > Metasound::Downcast ( [TUniquePtr](API\Runtime\Core\Templates\TUniquePtr)< [ISender](API\Plugins\MetasoundFrontend\ISender) > && InPtr ) }